If you want to give survivors corrosion stacks quickly, spawn in and get yourself killed so that the earlier you damage them, the more corrosion stacks they'll gain while staying in the same area with the Corrosive Gas Buff.

Description:When you grab a survivor with your tongue, all other survivors around a small radius of your victim will be stunned for 2.5 seconds.
<Survivors can't be stunned within 10 seconds of another stun>

Tips on Buff Usage:

You can use the Aggressive Tongue Impact Buff in strategic ways... to get your target into a better position for an infected attack or to stop them from interrupting one already happening.